I have used Look pedals since I ditched clips and straps in the early 90’s. My knees have started to give me problems lately, so I figured I’d give Time a try since they’re supposedly easier on the knees. I’m leaning towards the older RXS design, as opposed to the newer Xpresso models, which seem to be a “new and improved” version of the Iclic model. I have read that one should lower their seat when using Time pedals. I’m sure it can’t be more than a few millimeters, but does anyone know what the “correct” amount would be? Thanks. (Please, Speedplay users do not regale me with how wonderful your pedals are. At least not yet, as I may end up trying those at a later date!)

I'm curious why you think any Times are better or worse for knees. To me, the key is getting the cleat adjusted properly and that includes shims. Sorry I've never used Time for the road but was really glad to not be using squeaky old Looks anymore. I use Time mtb pedals on all my bikes. Never could dial in the road cleats to get even wear and that meant the platform was constantly changing which to me would be one potential benefit for speedplays if you have to have road pedals. Time would seem to have similar problems to shimano or Looks.

Another thought, from the knee perspective. There are some of us for whom float prevents us from locating the toe-in/toe-out correctly for our knees. For my knees to track properly, I must have cleats that force a little toe-in. With pedals that float, either that toe-in is not there, or I am doing that toe-in with my muscles which loads my knees in exactly the wrong direction. (I need a lot of forced toe-in for my right foot and a very small amount for my left. It looks odd, but my knees have been happy with this set-up for 35 years and let me know in the first mile or two their discomfort if I do anything else.)

I know my condition is unusual, but I am not alone. That famous racer whose name cannot be uttered rode LOOK pedals for years with the no-float black cleats. Not until Shimano made a no-float possible pedal-cleat system did he become brand loyal.

Assuming you are using the same shoes for both pedal systems I think the best way to figure this out is to clip your shoe into the pedal and measure from the inside sole where the shoe crosses the pedal spindle to the top or your saddle and then make sure you duplicate that same measurement with your new pedals. In theory, if your shoes stay the same and you don't have to add an adapter plate of any kind to your shoes to use Time then you could just measure from the pedal platform to your saddle on your current setup and then again with the Time pedals.